1. Field
Example embodiments relate to a recessed transistor and a method of manufacturing the same. Other example embodiments relate to a recessed transistor including a gate structure that is formed in a recessed structure of an active region and a method of manufacturing the recessed transistor.
2. Description of the Related Art
As semiconductor devices become more highly integrated, it is desirable to decrease widths of each pattern and the intervals between the patterns of the semiconductor device. In order to decrease the width (and intervals) of each pattern, it is desirable to obtain a more precisely and accurately formed minute pattern. In the semiconductor device, a width of a gate may decrease (or be narrowly formed) in proportion to a decrease in a design rule of the semiconductor device in order to develop (or form) a semiconductor device including a recessed gate electrode, which has an elongated effective channel length with a minute (or substantially smaller) width.
FIG. 1 is a diagram illustrating a cross-sectional view of a conventional recessed gate structure. FIG. 2 is a graph showing an effective charge density per unit gate length along a surface of a channel in the recessed gate structure in FIG. 1.
Referring to FIGS. 1 and 2, the conventional recessed gate structure 10 includes a semiconductor substrate 1 having a recess R, a gate insulation layer 2 formed along a side surface and a bottom surface of the recess and a gate electrode 3 formed in the recess.
Comparing the recessed gate structure 10 to a planar gate structure including a channel that is formed along a gate insulation layer on a semiconductor substrate, the recessed gate structure 10 may have a larger channel length. The effective charge density per the unit gate length may change according to the shape of the recess. The effective charge density per the unit gate length may change substantially according to a profile of the gate insulation layer (indicated by arrows in FIGS. 1 and 2) on the bottom surface of the recess such that swing characteristics are undesirable. The gate structure may have decreased electrical characteristics.